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A telescope designed to look back in time

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Hubble has helped make major discoveries but there are limits to how far it can see into space

The James Webb Space Telescope will work in the infra-red and be able to see objects that formed 13 billion years ago

Scientists also believe the new telescope will be able to detect planets around nearby stars

London (CNN)If you're hunting for the earliest galaxies and clues about potential life on other planets you are going to need a very big mirror and a golf ball of gold.

They are both necessary for the construction of The James Webb Space Telescope (JWST), intended as the successor to the Hubble instrument that has been operating in space for 25 years.

It's going to be a tough act to follow. Hubble has returned spectacular images during the past quarter century but also helped scientists discover that almost every galaxy has a massive black hole at its heart and that the expansion of the universe is speeding up.

But there are limits to how far it can see. Now scientists are working on an alternative way to peer into the past and search space for signs of life with JWST -- scheduled to launch in October 2018 on an Ariane 5 rocket from French Guiana.

Instead of studying visible and ultraviolet light like Hubble, the JWST will work in the infra-red spectrum, allowing scientists to detect more distant targets.

The new telescope requires a huge mirror of 25 square meters (about 270 square feet) -- and a golf ball of gold (about 48 grams or 1.7 ounces) to optimize it for infra-red light. It is then coated with glass.

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Telescope price tag is astronomical

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Telescope price tag is astronomical02:22

But technology like this doesn't come cheap. According to NASA, the mission, which is in collaboration with the European Space Agency (ESA) and the Canadian Space Agency (CSA) and involves a total of 14 countries, will cost $8.5 billion.

NASA says that the project has four main goals -- namely, to search for the first galaxies formed after the Big Bang, find out how galaxies evolved, observe the birth of stars and planets and investigate the potential for life on other planets

Scientists hope the telescope will be able to tell us more about objects that formed 13 billion years ago -- about 700-800 million years after the Big Bang.

NASA says JWST should be able to operate for between five and 10 years, restricted only by the amount of fuel it has to maintain orbit and the ability of the electronics to stand up to the harsh space environment.